Well, it's an extra layer of protection anyway...:)

If you're following the current thread on 'Roll your own UFH?' you will have noticed a pic showing a tidy little DIY UFH install - linear, not bifular tis true, but seemingly AOK for all that. Look closer and you will notice an extra polythene membrane above the insulation and below the pipes.

We used, many moons ago, before the invention of Weetabix and PIR foam, to fit polystyrene panels with a bonded membrane, which had a number of purposes. Stopping screed interfering with insulation values, allowing a decent 'catch' for the barbed staples or rails commonly used (rails tend to be stick-on, or staple-thru nowadays, but you get my drift) and others.

With the advent of foam sheet with foil barrier, it was mooted that screed could be applied directly to the foil without detriment. The science has moved on and it is apparent that OPC damages the foil layer.

Also, there have been recorded instances where, due to inadequate taping of sheet joints or edges, and especially with the more liquid flo-screeds becoming common, that the entire foam layer has literally been found to float as liquid screed finds its way underneath.

The thread is to educate possible DIYers of the danger and ask what experience anyone has had of the new membrane. I find it a pain to fit, but it does the job. Not that I had problems before, but it is, as I say, an extra layer of protection.

The 'floor' is yours....

Well bugger me - about 2 days too late for half my floor area!!! All carefully taped etc before the concrete went in. Never mind - should last 30 years? I'll put it in for the rest. Asked the architect about it but he was not aware of this even though (when I looked carefully) it is part of the BBA Cert!!

Posted By: borpinWell bugger me - about 2 days too late for half my floor area!!! All carefully taped etc before the concrete went in. Never mind - should last 30 years? I'll put it in for the rest. Asked the architect about it but he was not aware of this even though (when I looked carefully) it is part of the BBA Cert!!

Did you screed or did you concrete - may make a differece depending on the concrete you are using. Should be interesting to see what Buiding control say about ours, as we are following the makers recommendations, using Tetris insulation with C35 concrete on top - no need for protective layer.

Its on the warm side of the insulation, so it should reduce the risk of condensation problems.

David

Can you define 'always' in time-terms finny? I didn't know about this til a couple of months ago. And I'm not sure that all BCOs or architects besides borpins are aware - even now.

Sorry borpin, should have done this one a few days ago...

Pugliese - is the lack of layer required due to the insulation, or the fact of the medium being concrete?

Crusoe..
First two nu heat systems 2006 and 2007. Can't be sure if it was their spec or BCOs, as I said I was just a subby. Actually I think I got the job because I am part Dane and I reckon they just assumed I would know how to do it.

Posted By: Pugliese

Pugliese - is the lack of layer required due to the insulation, or the fact of the medium being concrete?

Suspect it will be the insulation as it is so tough you can happily jump up and down on it, but for a definitive answer I'll find out and report back.

Tetris as an XPS has a closed cell makeup and does not absorb moisture unlike say polyrethane, so does not need any protection

Interesting Pugliese - is Tetris, despite its toughness, not itself 'burnt' by the OPC leaving these pockets, or is it too soon/too new a product to tell?

Thanks for that. I have a client who is about to do this and encouraged him to come on here and read about this from the horse's mouth. Not calling you a horse of course.... Is there a huge difference in cost?

Posted By: PuglieseAttached is a pic - sorry it is not the best but gives you an idea

20120808_091520 (2).jpg

All I see is some text similar to the above quote. It's supposedly an image and if I click on "View Image" I see:

Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 3264 bytes) in /home/greenbui/public_html/newforum/extensions/InlineImages/image.php on line 14

So I think there's something wrong with the picture or the forum software!

www.thomasarmstrong.co.uk is the link - from my brief viewing it does appear to be designed for exclusive use with block and beam flooring - or am I missing something?